Situation Report: Lassa Fever Death in Iowa

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On October 28, 2024, the Iowa Department of Health and Human Services (IDHHS) reported a fatal case of Lassa fever in a patient who had recently returned from a trip to West Africa. This was the ninth known occurrence since 1969 of Lassa fever in a traveler returning to the United States.

About Lassa Fever

Lassa fever is an acute, febrile illness caused by the Lassa virus and is endemic in parts of West Africa, including Nigeria, Sierra Leone, Liberia, and Guinea. In West Africa there are between 100,000 and 500,000 cases of Lassa fever, and approximately 5,000 deaths related to the disease, every year.

Lassa Virus Transmission Risk

The Lassa virus is spread by the “multimammate rat” found throughout Sub-Saharan Africa, and the virus is carried in this rodent’s urine and droppings. Infection typically occurs by touching or eating contaminated materials such as food or sweeping contaminated areas.

In rare cases, the virus can be transmitted person-to-person through direct contact with blood and other bodily fluids. Lassa fever is not spread through casual contact, such as hugging, shaking hands, or sitting near someone, and patients are not believed to be infectious before symptoms begin. Regarding the case in Iowa, the CDC has confirmed that the patient was not symptomatic during their travels and therefore the risk to fellow airline passengers is very low.

The Lassa virus can spread in health care settings when not using proper personal protective equipment (PPE) or properly sterilizing equipment.

Signs and Symptoms of Lassa Fever

Signs and symptoms of Lassa fever typically occur 1-3 weeks after the patient comes into contact with the virus. Lassa virus can cause a wide range of clinical signs and symptoms, from asymptomatic or very minimal symptoms to the severe manifestation, a viral hemorrhagic fever. Early symptoms of Lassa fever are similar to those of other common viral illnesses, including fever, chills, malaise, and muscle aches, making it difficult to identify early on. 

For the majority of Lassa fever virus infections (approximately 80%), symptoms are mild and are undiagnosed. However, some people may develop more serious symptoms, including hemorrhaging, respiratory distress, vomiting, facial swelling, pain in the chest, back, and abdomen, and shock. Neurological problems, such as hearing loss, can occur in both mild and severe cases.

Screening and Diagnosis

In cases of suspected Lassa fever in the U.S., diagnostic testing should be coordinated with local public health officials to arrange for sample evaluation in an appropriate diagnostic facility.

Read the NETEC blog post on testing for Lassa fever.

See the CDC’s Clinical Screening and Diagnosis for VHFs guidance.

Infection Prevention in Health Care Settings

When presented with a potential Lassa virus infection, clinicians and health care workers should follow an identify, isolate, and inform strategy, as outlined in NETEC’s webinar The I’s Have It: Identify, Isolate, and Inform. Patients infected with or suspected to be infected with Lassa virus should be cared for in a biocontainment unit and health care providers should follow personal protective equipment (PPE) guidance to prevent person-to-person spread. Learn about personal protective equipment (PPE) recommendations when caring for a patient with Lassa fever. 

Additional Resources for Health Care Personnel

To help health care facilities prepare, NETEC developed the Health Care Facility Viral Hemorrhagic Fever Preparedness Checklist. This tool helps health care facilities assess their readiness to identify, isolate, inform, and treat patients with suspected or confirmed viral hemorrhagic fevers. It guides a review of immediate care capabilities and offers resources to address any preparedness gaps.

For more on the pathogenesis, clinical features, diagnostics, vaccines, and treatments for Lassa fever, check out “Lassa Virus Infection: a Summary for Clinicians,” by the Science Working Group of the NETEC Special Pathogens Research Network (SPRN).